|Military Aviation Organization Symbols Key|
(+) Placed to the right of the symbol indicates that a unit is substantially reinforced.
(–) Placed to the right of the symbol indicates that a substantial part of the unit is detached. It may also be used to indicate that subordinate elements are operating at extended distances from, and semi-independently of the parent unit.Please note that some countries did not have a separate Naval Aviation arm, i.e. aircraft and flying units under control of the corresponding navy, so that the symbols indicated under 'Naval Aviation' were, of course, in these cases, air force unit types. The designations of flying units in the various air forces varied, as did the rank of the comanders of the various echelons. Air arms owned or even influenced by the army tended to have the same designations and ranks as ground units, possibly with the prefix 'Flying ...' or 'Air ...'. Rank is not the final indication of the size of the unit, or even the authorized rank of the commander. Take the Greek Air Force in October 1940 for example, where company-sized flying units were commanded by Lieutenant Colonels as well as Majors and Captains. On the other hand a low state of mobilization might mean that many officers commanding were one or two ranks under the authorized ones. For example, on 7 December 1941 not one USAAF Air Group (regiment-sized unit) was commanded by a full Colonel. In other air forces, in some cases, Captains commanded regiment or even brigade-sized units.
The number of aircraft in a unit varied. Company-sized flying units had 6 to 12 aircraft. Battalion-sized flying units 12 to 24 aircraft. Regiment-sized units had 20 plus. Units with small aircraft (one or two crew members) tended to have more aircraft in them than those with large aircraft (which had more engines, a larger aircraft crew, more numerous gound maintenance men, etc.). In addition, the difficulty is also in determining whether the numbers indicated are 'on hand' as opposed to 'authorized' aircraft, or include 'reserve', 'sidelined', 'in maintenance', etc. equipment.